Cable attachment for a lumbar support

ABSTRACT

An adjustable lumbar support mechanism includes a flexible support member, a cushioning yoke, and a cable assembly. The flexible support member has oppositely disposed first and second longitudinal ends. The cushioning yoke has a first end attached to the flexible support member proximate to the first longitudinal end of the flexible support member. The cushioning yoke extends to its second end which is disposed between the first end of the cushioning yoke and the second end of the flexible support member. The yoke has a plurality of undulations disposed between the yokes first end and second end. The cable assembly has a sleeve and a cable slidably disposed therein. The sleeve has a first end attached to one of the second end of the cushioning yoke and the second end of the flexible support member. A first end of the cable is attached to the other of the second end of the cushioning yoke and the second end of the flexible support member.

This application is a continuation in part of U.S. patent applicationSer. No. 08/606,257, filed on Feb. 23, 1996, and issuing as U.S. Pat.No. 5,609,394 on Mar. 11, 1997.

FIELD OF THE INVENTION

The present invention relates to lower back or lumbar supports forseats, and more particularly to adjustable lumbar supports used inseatbacks.

BACKGROUND OF THE INVENTION

Lumbar supports employing cables as a means of adjusting the lumbarsupport commonly attach the cable directly to the flexible supportmember. This places a high level of stress on the flexible supportmember at the location of the cable attachment, particularly when thelumbar support is subjected to an impact load.

It is desired to provide a lumbar support employing a cable operatedadjustment mechanism in which the connection of the cable to theflexible support induces a relatively low magnitude of stress in theflexible support member.

SUMMARY OF THE INVENTION

An adjustable lumbar support mechanism includes a flexible supportmember, a cushioning yoke, and a cable assembly. The flexible supportmember has oppositely disposed first and second longitudinal ends. Thecushioning yoke has a first end attached to the flexible support memberproximate to the first longitudinal end of the flexible support member.The cushioning yoke extends to its second end which is disposed betweenthe first end of the cushioning yoke and the second end of the flexiblesupport member. The yoke has a plurality of undulations disposed betweenthe yokes first end and second end. The cable assembly has a sleeve anda cable slidably disposed therein. The sleeve has a first end attachedto one of the second end of the cushioning yoke and the second end ofthe flexible support member. A first end of the cable is attached to theother of the second end of the cushioning yoke and the second end of theflexible support member.

An alternative adjustable lumbar support mechanism includes a flexiblesupport member and a cable assembly. The flexible support member hasoppositely disposed first and second longitudinal ends. The firstlongitudinal end has clamping features adapted to rotatably attach thefirst longitudinal end to a first horizontally disposed bar. The secondlongitudinal end is adapted to be slidably connected to a secondhorizontal disposed bar. The cable assembly has a sleeve and a cableslidably disposed therein. A first end of the cable has a hook fixedthereto, the hook being adapted to engage the first bar. The sleeve hasa first end connected to the second end of the flexible support member.Displacement of the cable within the sleeve causes the flexible supportto arch responsively thereto.

These and other features of the present invention will become apparentto one skilled in the art from the following detailed description andthe appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a four-way lumbar support in a seatbackframe.

FIG. 2 is a rear view of the four-way lumbar support and seatback frameof FIG. 1.

FIG. 3 is a side view of the four-way lumbar support of FIG. 1 adjustedto provide minimal lumbar support.

FIG. 4 is a side view of the four-way lumbar support of FIG. 1 adjustedto provide maximum lumbar support at a first or lowest apex verticalposition.

FIG. 5 is a side view of the four-way lumbar support of FIG. 1 adjustedto provide maximum lumbar support with the apex adjusted to a second ormaximum vertical position.

FIG. 6 is a rear view of a two-way lumbar support in a seatback frameemploying a first alternative means for connecting the cable to thesupport member.

FIG. 7 is a side view of the lumbar support of FIG. 6 in the directionof arrows 7.

FIG. 8 is a rear view of a two-way lumbar support in a seatback frameemploying a second alternative means for connecting the cable to thesupport member.

FIG. 9 is a side view of the lumbar support of FIG. 8 in the directionof arrows 9.

FIG. 10 is a rear view of a two-way lumbar support in a seatback frameemploying a third alternative means for connecting the cable to thesupport member.

FIG. 11 is a side view of the lumbar support of FIG. 10 in the directionof arrows 11.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

A four-way lumbar support 10 as shown in FIGS. 1 and 2 is supported by aseatback frame 12 having a first or lower horizontally disposed bar 14and a second or upper horizontally disposed bar 16 engaging oppositeends of four-way lumbar support 10. A flexible single piece supportmember 18 is engaged by means for longitudinally subtending 20 and anapex shift mechanism 22.

The single piece support member 18 has a central body 24 with a first orlower longitudinal end 25 pivotably attached to first horizontallydisposed bar 14, and a second longitudinal end 26 slidably engagingsecond horizontally disposed bar 16. Four support fingers 27 extendtransversely outwardly from each side of central body 24. Of coursesupport member 18 may have more or fewer support fingers 27 dependingupon the specific seat configuration. First longitudinal end 25 includesan inside clamping member 28 and outside clamping member 30, best shownin FIGS. 2 and 3. Inside clamping member 28 and outside clamping member30 deflect from a first position, shown in phantom in FIG. 3, to receivefirst horizontally disposed bar 14 and deflect to the second position,shown in solid lines, trapping bar 14 and thereby providing pivotableengagement between first longitudinal end 25 and first horizontallydisposed bar 14.

Second longitudinal end 26 has inside holding member 32 and outsideholding members 34 engaging second horizontally disposed bar 16. Insideholding member 32 and outside holding members 34 are spaced apart fromeach other as shown in FIGS. 3-5 a distance approximately equal to adiameter of second horizontally disposed bar 16, enabling slidingmovement of second longitudinal end 26 relative to second horizontallydisposed bar 16 a distance approximately equal to the length of outsideholding member 34.

A subtending yoke 36 has a lower side 37 passing through an aperture ina bottom anchor 38 which is fixed to inside clamping member 28, therebypivotably attaching yoke 36 to support member 18. Subtending yoke 36 hasan engaging hook 39 on one side which engages a free end of lower side37 to enable both sides of yoke 36 to react against lower side 37 whenthe yoke sides are in tension.

A subtending cable assembly 40 engages a U-shaped slot 41 in yoke 36with a cable end 42 of a subtending cable 43. A subtending cable housingor sheathing 44 encloses a portion of subtending cable 43 and extendsfrom a first reinforcing sleeve 46 engaging a tab 48 of inside holdingmember 32 to an actuator housing 50 including an electric drive motor52.

Apex shift mechanism 22 includes an apex shift linkage 54 having anH-shaped first shift link 56 pivotably connected at a hinge point to aY-shaped second shift link 58. A lower portion of first shift link 56straddles bottom anchor 38 and has a first aperture 60 which receiveslower side 37 of yoke 36. Free end of lower side 37 is removed fromconnecting hook 39 and passes through the aligned first aperture 60 andbottom anchor aperture to pivotably connect first shift link 56 withsupport member 18. An upper portion of first shift link 56 captures alower end of second shift link 58 and has a second aperture 62 alignedwith a first aperture 64 through the lower end of second shift link 58.A pin 66 passing through apertures 62 and 64 defines the hinge point orrotational joint between first and second shift links 56 and 58. Therotational joint can alternatively be provided any other suitablestructure, such as a snap-in feature with a pair of engaging bumps anddimples. A reinforcing stamping 68 fixed to support member 18 includes asnap mount 70 which receives an upper pin 72 disposed between open armsof second shift link 58 for pivoting within the snap mount 70.

A cable aperture in second shift link 58 located opposite the hingepoint from support member 18 receives a cable housing 78 of apex shiftcable assembly 80. Cable housing 78 extends to an apex shift actuatorhousing 81. An apex shift cable 82 is disposed within cable housing 78and extends beyond cable housing 78 to engage a molded cable anchor 83fixed to support member 18 which receives a cable end 84. Molded cableanchor 83 is fixed to support member 18 at a location between bottomanchor 38 and snap mount 70 and proximate to a preformed bend 88 insupport member 18 bowing outward away from apex shift linkage 58. Anexposed length of cable 82 extending beyond cable housing 78 to cableend 84 is varied in length by actuator 81 with the energization of anelectric drive motor 86.

The two actuator/drive motor combinations, 50, 52 and 81, 86 are mountedto the lowermost of the support fingers 27 in the embodiment shown.However, it is anticipated that the actuator/drive motor combinationscould be mounted elsewhere, as may be required for the particular seatinto which the lumbar support is to be placed. While electric drivemotors are shown in the present embodiment, it should be appreciatedthat other drive means, such as hand operated cable displacementmechanisms, can be substituted.

The four-way lumbar support operates in the following manner. Thefour-way lumbar support 10 as shown in FIG. 3 is effectively providingno enhancement of lumbar support. Support member 18 is essentiallyundeflected from its unloaded shape. By displacing cable 43 to shortenthe length of cable 43 disposed between the U-shaped slot 41 in yoke 36and the cable housing 44, support member 18 bows outward, defining anoutermost point, or apex 90 at the support finger 27 which is secondfrom the top. It is understood that the precise location of apex 90 ismerely exemplary and will vary with the specific design of the lumbarsupport 10. As the exposed cable length is shortened, secondlongitudinal end 26 slides along second horizontally disposed bar 16 asfirst longitudinal end 25 pivots about first horizontally disposed bar14 until second horizontally disposed bar 16 is engaged by tab 48 toprevent further displacement.

The apex 90 is shifted upward and made more pronounced by shortening thelength of exposed cable 82. Energization of drive motor 86 results in ashortening of the portion of apex shift cable 82 exposed between cablehousing 78 and molded cable anchor 83. The change in length occurs withthe pivoting of first shift link 56 relative to second shift length 58,increasing the angle therebetween and likewise increasing a distancebetween bottom anchor 38 and snap mount 70 which tends to straighten outa stamped or preformed bend 88.

The amount of bowing can be varied between the minimum and maximum shownin FIGS. 3 and 4 respectively by merely varying the displacement ofcable 43 adjusting the exposed length of cable 43 to an intermediatelength to provide the amount of bowing desired. Reversal can be achievedby reversing the change in exposed cable length. Similarly, theadjustment of the location of apex 90 can be controlled between thatshown in FIGS. 4 and 5 by controlling the exposed length of cable 82.The apex 90 is shifted upward by shortening the exposed length of cable82 . The apex is shifted downward by increasing the exposed length ofcable 82.

It should be appreciated that the means for attaching the subtendingcable can be varied from that shown in FIGS. 1-5. Three alternativemeans are shown in use with two-way lumbar supports in FIGS. 6-11.

A first cushioning yoke 92 is shown in FIGS. 6 and 7 as an alternativeto subtending yoke 36A in a two-way lumbar support 94. Cushioning yoke92 has the shape of an elongated rectangle and is fixed at a lower endby rivets 96 to a lower end of the support member 98. Cushioning yoke 92has a rectangular aperture 100 centered therein to accommodateinstallation of apex shift mechanism 22, enabling conversion of two-waylumbar support 94 to a four-way lumbar support. Cushioning yoke 92 has aplurality of wave shaped undulations 101 formed along its length.Approximately 11/2 wavelengths are formed by undulations 101.

A bowden-type cable assembly 102 having an outer sleeve 104 with a cable106 slidably disposed therein extends from a displacement mechanism 103to support member 98. Sleeve 104 terminates in an engagement block 108formed at an end of sleeve 104. Engagement block 108 is received by apocket portion 110 of an upper portion of support member 98. Cable 106passes out through engagement block 108 and a slot 112 through pocketportion 110. A portion of engagement block 108 passes through slot 112to keep block 108 centered in pocket portion 110. An enlarged cable end114 is received by a hook portion 116 at the top of yoke 92. As long ascable 106 is maintained in tension, engagement block 108 and cable end114 will remain firmly seated in pocket portion 110 and hook portion 116respectively.

The lower portion of support member 98 is pivotably attached to lowerbar 14 in substantially the same manner as support member 18. Theoutside clamping members 30 have each been narrowed, and a pair ofback-up tabs 118 have been added between the inside and outside clampingmembers. Back-up tabs 118 help maintain bar 14 in its desired positionrelative to clamping members 30 and 28.

The upper portion of support member 98 is slidably disposed over upperbar 16. The upper portion of support member 98 has a pair of outermembers 120 with engaging beads 122 which stiffen outer members 120 andpresent a minimum contact area surface to bar 16. Retention of outermembers 120 against bar 16 is ensured by a retention tongue 124 whichprojects rearward from the top of support member 98 a distanceapproximately equal to the diameter of bar 16, and then extends downwardparallel to engaging beads 122, to enclose bar 16 therebetween. Pocketportion 110 is disposed at a lower end of a U-shaped section which wrapsaround retention tongue 124.

Displacement mechanism 103 employs a lead screw (not shown) rotatablydisplaced by rotation of a handwheel 128 to produce axial displacementof cable 106. It should be readily apparent that a motorized drivesystem can be substituted for displacement mechanism 103.

The system of FIGS. 6 and 7 operates in the following manner. Supportmember 98 is shown in an essentially undeflected shape in FIG. 7,providing minimal lumbar support. Handwheel 128 is rotated in a firstdirection to increase the amount of lumbar support provided. As cable106 is retracted, the distance between pocket portion 110 and hookportion 116 decreases, resultantly causing support member 98 toincreasingly bow outward. Coincident with this increased bowing, theupper portion moves downward, with beads 122 sliding downward on bar 16.When the desired amount of lumbar support is achieved, then handwheel128 is released. When a decrease in lumbar support is desired, handwheel128 is merely rotated in a direction opposite the first direction.

Although the undulations 101 in yoke 92 will tend to straighten as theapex is shifted further outward, the principle benefit of theundulations 101 is in reducing the stress on the lumbar supportassociated with impact loading. Impact loadings occur in rear-impactcollisions. When an occupied seat is suddenly accelerated forward, as ina rear impact, the occupant is pushed back into the seat and against thelumbar support. It is highly desirable that the lumbar support maintainits functionality after sustaining an impact, yet provide someflexibility to reduce loading stresses at the pocket portion 110 andhook portion 116. The cushioning yoke achieves the objective of reducingthe stresses for impact loading conditions.

A second alternative means for attaching the subtending cable 102 shownin FIGS. 8 and 9 is substantially the same as that shown in FIGS. 6 and7, except that the cable and sleeve ends, 116 and 108 respectively, andtheir associated retention features 110 and 116, are reversed withrespect to support member 98 and yoke 92. Whether the cable sleeve isoriented to come from above, as shown in FIGS. 6 and 7, or from below,as shown in FIGS. 8 and 9, is a matter of design choice, largelycontrolled by packaging parameters.

A third alternative means for attaching the subtending cable 102 shownin FIGS. 10 and 11 is also substantially like that shown in FIGS. 6 and7, except that no yoke is provided. Cable 106 instead has a hook 103which passes through a notch 132 in clamping member 28 to directlyengage bar 14. While this configuration does not have the cushioningeffect associated with yoke 92, it achieves an improved distribution offorces to minimize the localized stress at the point of attachment ofcable 106 to support member 98. By using hook 130 to engage bar 14, theload in cable is distributed across clamping member 28 instead of alocalized point.

The preceding description is exemplary rather than limiting in nature. Apreferred embodiment was disclosed to enable a skilled artisan topractice the invention. Modifications are possible without departingfrom the scope of the present invention, which is limited only by thefollowing claims.

We claim:
 1. A lumbar support mechanism comprising:a flexible supportmember having oppositely disposed first and second longitudinal ends; acushioning yoke having a first end attached to the flexible supportmember proximate to the first longitudinal end of the flexible supportmember and the cushioning yoke extending to a second end thereofdisposed between the first end of the cushioning yoke and the second endof the flexible support member and the yoke having a plurality ofundulations disposed between the yoke's first end and second end; and acable assembly having a sleeve and a cable slidably disposed therein,the sleeve having a first end attached to either the second end of thecushioning yoke or the second end of the flexible support member and thecable having a first end attached to the other of the second end of thecushioning yoke and the second end of the flexible support memberwherein the undulations tend to straighten when the flexible member issubjected to an impact loading.
 2. A lumbar support mechanism as claimedin claim 1 wherein a means for longitudinally subtending the supportmember is disposed on the support member in alignment with an aperturein the yoke, enabling the flexible support member to shift betweenpositions providing maximum lumbar support and minimum lumbar supportwithout inducing contact between the means for longitudinally subtendingthe support member and the yoke.
 3. A lumbar support mechanism asclaimed in claim 1 wherein a means for longitudinally subtending thesupport member is disposed on the support member in alignment with anaperture in the cushioning yoke, thereby enabling the flexible supportmember to shift between a maximum lumbar support position and a minimumlumbar support position without inducing contact between the yoke andthe means for longitudinally subtending the support member.
 4. A lumbarsupport mechanism as claimed in claim 1 wherein the first end of thesleeve is attached to the second end of the cushioning yoke and thefirst end of the cable is attached to the second end of the flexiblesupport member.
 5. A lumbar support mechanism as claimed in claim 1wherein the first end of the sleeve is attached to the second end of theflexible support member and the first end of the cable is attached tothe second end of the cushioning yoke.
 6. A lumbar support mechanismcomprising:a flexible support member having oppositely disposed firstand second longitudinal ends, the first longitudinal end having clampingfeatures adapted to rotatably attach the first longitudinal end to afirst horizontally disposed bar and the second longitudinal end havingslidable connecting features adapted to be slidably connected to asecond bar having a horizontally disposed major axis; and a cableassembly having a sleeve and a cable slidably disposed therein, a firstend of the cable having an engaging feature fixed thereto, the engagingfeature being adapted to engage the first bar, the sleeve having a firstend connected to the second end of the flexible support member whereindisplacement of the cable within the sleeve causes the flexible supportmember to arch responsively thereto.
 7. A lumbar support mechanismcomprising:a substantially planar flexible support member havingoppositely disposed first and second longitudinal ends; a yoke having afirst end attached to the flexible support member proximate to the firstlongitudinal end of the flexible support member and the yoke having asecond end disposed between the first end of the yoke and the second endof the flexible support member and the yoke having an aperture extendingbetween the first end and the second end thereof, and wherein the yokehas a plurality of undulations disposed between the yoke's first end andsecond end and wherein the undulations tend to straighten when theflexible support member is subject to impact loading; a cable assemblyhaving a sleeve and a cable slidably disposed therein, the sleeve havinga first end attached to either the second end of the yoke or the secondend of the flexible support member and the cable having a first endattached to the other of the second end of the cushioning yoke and thesecond end of the flexible support members, and wherein movement of thecable defines an apex formed in the flexible support member between theflexible support member's first and second longitudinal ends; and anapex shift mechanism disposed on the support member in alignment withthe aperture in the yoke, thereby enabling the location of the apex tobe shifted without inducing contact between the yoke and the apex shiftmechanism.